The proposed research seeks to establish the mechanism of nonstereospective hydrogen transfer by UDP-galactose-4-epimerase and to determine the rate constants for binding steps and hydrogen transfer steps as well as the kinetic isotope effects resulting from the replacement of substrate hydrogen by deuterium. In research on E. coli alpha-ketoacid dehydrogenase complexes the detailed pathways of electron and acyl group transfer will be traced by radiochemical and spectral methods. The mechanism of fluoropyruvate decomposition catalyzed by this enzyme will be determined by radiochemical methods.